Extruded hollow bars may be used as members in a support assembly. A cavity in a support assembly member may include a crush tube to provide additional support, bear a mechanical load at an attachment point of the member to a support assembly, etc. It is generally desired to retain a crush tube at or near a particular location in the cavity. For example, it may be desired to retain the crush tube at or near an opening in the support member. However, stresses at or near the opening can cause defects such as cracks and the like to form in the member, e.g., when the member is made of extruded aluminum. Such defects may in turn compromise the support assembly.